The art (and science) of making outdoor ice rinks in Minnesota

Minnesota is the land of 10,000 pond rinks: endless sheets of ice to skate or slap the puck across. Or at least that's how Minneapolis entrepreneur Fred Haberman sees it.

The outdoor-ice enthusiast, who founded the U.S. Pond Hockey Championships, says there's something about the brisk air, natural scenery and spontaneity of games that offers a pond-hockey player "a reunion with your younger self." It's a chance to skate for the love of the sport without the pressures inherent to an arena.

Decades ago, when Haberman discovered one of the city's most beloved rinks — the Norman Rockwell-esque, mansion-ringed one on Lake of the Isles — he couldn't get his skates on fast enough. "I was like a golden retriever," he joked.

Whether you glide gracefully on thin metal blades or flail like a cartoon character, public rinks bring Minnesotans together in a season that encourages sequestering at home.

And this year, outdoor ice should be especially popular, as COVID-19 restricts indoor gatherings.

The Minneapolis Park & Recreation Board has been making municipal ice rinks since the late 1800s and operates one of the state's largest systems. Like many communities statewide, the city no longer has as many rinks as it did during skating's heyday.

"Starting in the 1980s, it was really huge because the U.S. hockey team won the Olympic gold medal; Wayne Gretzky came to the L.A. Kings, and the 'Mighty Ducks' movies" were released, explained park operations manager Dave Bergstrom.

But despite the pandemic, 20 Minneapolis skating locations are open this season, sans the warming houses and loaner skates.

Though the rinks draw thousands of skaters each year, few people appreciate the difficulties of creating a sleek, level ice sheet out in the elements.

Bergstrom and Ann Fleischhacker, a longtime Minneapolis parks crew leader, retain much of the city's institutional ice-making knowledge, with 60 years of experience between them. Creating and maintaining outdoor ice rinks is as much an art as a science, they say. Not to mention a lot of work for park keepers who lug fire hoses, shovel ice shavings, and fight a natural nuisance known as frost boils to ensure a safe, pleasant skate.

Bergstrom and Fleischhacker advise park keepers to read terrain, temperature and sunlight to fine-tune their rink-making technique. And then, each year, the two assess each rink on everything from the neatness of its hockey nets to the smoothness of its ice, and recognize the best park with the Golden Nozzle award.

"I want ice that looks like indoor ice, outside," Bergstrom said.

Making ice

Fleischhacker knows the ins and outs of every city rink: which have the most shade, which have the deepest bowls (some are up to 3 feet thick in the center). She's thawed a frozen fire hydrant with a blow torch when necessary.

"I've probably made ice at every park," she said.

The most important thing to remember about rink-making, Fleischhacker said, is that you can't rush the process.

Park keepers usually get started around Thanksgiving by sealing all the field drains. Then they saturate the ground with sprinklers or 1-inch hoses, moving the water source frequently so it doesn't thaw frozen soil.

Once the rink's base has been established, staff need consistently cold weather — temperatures in the single digits — to flood. They attach a tool called a flood box (a large wooden case with slits in its sides) to a fire hose in order to diffuse the water stream.

Staff members build up the ice in layers, waiting until each coat freezes before adding the next.

Applying too much water at once can melt a channel in the ice. Or create shell ice, when a thin crust freezes on top, with water beneath.

To make rinks on the city lakes, staffers cut a hole in the ice and pump water to the surface. Lake rinks are inherently more hazardous, of course, and Fleischhacker can't stress enough how important it is to wait to skate until the ice is deemed safe — people have already fallen through several city lakes this season. And then there's the man-made danger of inconsiderate ice fishers augering holes in the middle of lake rinks.

Rink maintenance

Park staff members hope to get the rinks open by schools' winter breaks, but that goal has been harder to achieve in the past decade or so because of uncooperative weather, Bergstrom said.

Once the rinks are ready, an overnight maintenance crew sweeps up the skaters' ice shavings (or plows snow) seven days a week. Shortly after the park keepers' 5 a.m. shift begins, they refresh the rink's surface with another coat of water.

Staffers use an array of ride-on vehicles for removing ice shavings and snow, but much of the rink maintenance is done by hand: filling cracks with a bucket full of slush; chipping off ice with chisels and blades, or deploying tools of their own creation.

"We've tried all kinds of different homemade Zambonis," Bergstrom noted.

The most dramatic resurfacing tool is known as a tractor shaver, which has been used at least since the 1950s, Bergstrom said, when his father worked for Minneapolis' parks. It's a big sharp blade pulled by a tractor, and older models required an operator to skate behind the device, holding onto the top, to adjust its position and depth.

This wintry version of water-skiing was a thrilling ride, though hard on the legs, Fleischhacker recalled of the days she skated behind the blade on Lake of the Isles.

Abiding Mother Nature

When it comes to outdoor rink-making, warm weather is an obvious issue, but extreme cold isn't good, either. Low temps can cause a fresh layer of water to freeze too fast and become brittle, create ridges or not bond to the previous layer and crack.

An ill-timed snowfall can disrupt the process. So can blowing leaves, or any other dark objects underneath or embedded in the ice, which will absorb sunlight and cause melting. (Staff members sometimes cover dark spots with white field-marking paint to prolong the life of the ice.)

Should soil underneath an ice sheet start to thaw, gases released by decaying vegetation can create stinky yellowish bumps known as frost boils. Staffers can't do much but shave the boils down.

"You can't beat Mother Nature," Bergstrom admitted.

There's also not much that can be done to combat the effects of the climbing sun. By mid-February, maintaining ice starts to become a futile endeavor. But the melting rinks are also a sign that a new season of recreation will reveal itself soon, on the grass and ball fields beneath.

Rachel Hutton • 612-673-4569